A flexible polyurethane foam is produced by reacting a polyol and a polyisocyanate in the presence of e.g. a catalyst and a blowing agent. As the polyol, e.g. a polyoxyalkylene polyol produced by ring-opening polymerization of an alkylene oxide such as ethylene oxide or propylene oxide to an initiator having an active hydrogen atom, or a polymer-dispersed polyol obtained by polymerizing a vinyl monomer in the presence of the polyoxyalkylene polyol, is used. The alkylene oxide and the vinyl monomer accounting for a large part of initiators which are raw materials of the polyol, are compounds derived from petroleum.
In recent years, in consideration of environment, there has been a demand to increase the proportion of a non-petroleum type raw material in a polyol (hereinafter referred to as the biomass degree).
As the polyol using a non-petroleum type raw material, the following polymer-dispersed polyols are proposed.
(1) A polymer-dispersed polyol obtained by polymerizing a reaction mixture containing a vinyl monomer, a polyol and a modified hydroxy group-containing compound obtained by reacting castor oil with a polyol (Patent Document 1).
(2) A polymer-dispersed polyol having polymer particles obtained by polymerizing a vinyl monomer dispersed in a polyol containing a polyol derived from a plant (castor oil) and a low-monool-content polyol (Patent Document 2).
(3) A polymer-dispersed polyol having polymer particles dispersed in a polyolester polyol having hydroxymethyl groups, induced from a fatty acid or a fatty acid ester derived from a vegetable oil plant (Patent Document 3).
However, since the polymer-dispersed polyols in (1) and (2) contain polyols derived from petroleum in a large amount, the biomass degrees are not sufficiently high. Further, if the proportion of castor oil, which is a non-petroleum type raw material, is increased, it is not possible to produce a flexible polyurethane foam excellent in foam physical properties and its appearance. With respect to the polymer-dispersed polyol in (3), the production process of a polyester polyol having hydroxymethyl groups is long, whereby the cost tends to be high.
Patent Document 1: JP-A-9-31142
Patent Document 2: WO2007/020904
Patent Document 3: WO2006/065345